Use the Alt/Option and Ctrl/Cmnd key to change the operation of the pen tool. Holding down the Ctrl/Cmnd key will change the pen tool from the pen to the selection tool

When the pen tool is selected and you hover over a path the add new point tool appears

When the pen tool is selected and you hover over a point the pen tool changes to a black arrow selection tool that will select the point

When the pen tool is selected and you hover over a point and the Ctrl/Cmnd key is pressed the pen tool changes to the subtract point tool

When the pen tool is selected and you over a point and the Alt/Option key is pressed the pen tool changes to the Convert point tool (open sideways V)

When the pen tool is selected and you hover over a line segment and the Ctrl/Cmnd key is pressed the pen tool changes to the selection tool (solid arrow) and you can select and adjust the line segment

When the pen tool is selected and you hover over an anything but a point or a path and you hold the Ctrl/Cmnd key the pen tool changes to the marquis selection tool (a white arrow) and you can select multiple points by clicking and dragging

If the path is not visible because the layer or the shape is not selected and you have the pen tool selected and you press the Ctrl/Cmnd key the pen tool changes to the standard selection tool so you can select the layer or the path

If all of the points on the path are selected you must hold down the Ctrl/Cmnd key to change the selection tool to the direct selection tool (white arrow with a tail) to select a point or a line segment

It just takes a little getting used to but it is very easy to select points, lines, and marque select parts of a path or mask using the pen tool and modifier keys.

The key is entering into "point editing mode" which is done most easily by double clicking on a shape layer with the selection tool, THEN selecting an individual point. From there, the selection tool turns into a marquee-selection tool and can be dragged to select points.

Alternately twirling down the shape Shape Layer>Contents>Shape and clicking on 'Path' also gets you to path editing mode.

No doubt stuff that more experienced users have long known, but took me a while. Thanks all!